It's teabagging, but in video games. When playing online or split-screen in a First person shooter game, and you've just fragged someone, you walk over the opponent's digital carcass, and then press the crouch command repeatedly to embarass the victim while he or she respawns.

It is truly embarassing, and should only be done by professionals. This means you need to earn some respect before you teafrag somebody, or else you will face the wrath of the victim.